1. Field of the Invention
This invention relates to shoe machinery, and more particularly to inertia control devices on shoe roughing machines.
2. Prior Art
This invention is an improvement of the type of shoe machine illustrated in British patent specification No. 1,137,254. The prior machine performs a roughing operation on marginal portions of shoe bottoms. The machine comprises a shoe support, tool supporting means for supporting two rotary roughing tools in tandem relationship lengthwise of the shoe support, means for controlling the pressure applied between the tools and the bottom of a shoe supported by the shoe support, and means for effecting relative movement between the shoe support and the tool supporting means to permit the tools to operate progressively along marginal portions of the shoe bottom at opposite sides thereof.
In the prior machine, cam means in the form of a flat template controls the relative movement of the tools with respect to the shoe being operated upon. The movement controlled, extends lengthwise and widthwise of the shoe support. Fluid pressure operated means is provided to control the pressure between the tool and the shoe bottom, permitting control of the heightwise position of the tool with respect to the shoe.
The pressure between the tool and the shoe bottom is variable to permit efficient operation upon shoes having a pronounced lengthwise curvature, e.g. high-heeled ladies' fashion shoes. The tool, in progressing from the toe end to the heel end of a shoe, firstly operates "uphill" from the toe portion to the ball region of the shoe bottom, and thereafter operates "downhill" from the ball region to the waist region of the shoe bottom and towards the heel seat portion thereof. When the tool is operating "uphill", it will tend to "dig" into the material of the marginal portion of the shoe bottom, whereas on the "downhill" operation, it will tend, because the shoe bottom is in effect falling away from it, to "bounce". The facility of varying the pressure, as mentioned earlier, can be used successfully to avoid any uneven roughing which would otherwise result.
It has been found, however, that with the machine described, the mass of the tool supporting means gives rise to relatively high inertia forces, so that the operating speed of the machine may in some circumstances have to be set at a level which is lower than is acceptable to a shoe manufacturer.
It is one of the various objects of the present invention to provide an improved apparatus suitable for use in performing a roughing operation on marginal portions of shoe bottoms, permitting higher operating speeds of the machine than has previously been the case.